Companies in the business of selling or licensing digital images for use by others and companies that provide digital images for incorporation into custom products may have tens or hundreds of thousands of photographs and illustrations available for searching by their customers. How to efficiently and easily search a very large number of digital images to locate a particular image having a desired style or content has been a chronic issue and continues to pose difficulties.
The keyword, which can be either a single word or a phrase, is the usual tool employed for searching an image database for an image having a particular desired style, feature, or content. Each image typically has a number of associated searchable keywords suggested by the image. Because different searchers may have different interests and requirements, a variety of different keywords are typically assigned.
For example, keywords typically describe the type, shape and other characteristics of the image that might be relevant to a searcher, such as Indoors, White Background, Photograph, or Square, and may specify the quantity of people or things, such as No People or Two Animals. Keywords also typically include the generic name for each significant object in the image, such as Boy, Flag, Mountain, or whatever is deemed appropriate and relevant by the individual assigning the keywords. In some cases, additional keywords may be used that are either more descriptive about a particular object in the image, such as Beagle, Age 8-10, New York City, or Brown hair, or a broader characterization of an object, such as Animal or Mammal. Keywords may identify a family relationship indicated in the image, such as Mother, or an occupation, such as Teacher, or may relate to identifiable activities taking place in the image, such as Running, Laughing, or Dining. Other keywords may identify abstract concepts or emotions conveyed by the image, such as Love, Celebration, Confidence, or Pride. Because of the many possible ways of characterizing an image and its component elements and features, it is not at all uncommon for an image to have twenty or more keywords.
While user-entered keywords are useful in screening for images of a general type or containing a particular object, the usual keyword searching system is not well suited to the process of trying to find additional images that are similar to an image being viewed. If a user wants to see additional similar images, the prior art approach is typically to present the user with a list of the keywords associated with the current image and allow the user to select individual keywords from the list to be used for another keyword search. This requires the user to study the current image and make a subjective judgment on a keyword-by-keyword basis of whether or not the aspect of the image associated with each keyword is relevant to the image that the customer hopes to find.
Some experienced users may be proficient at using keyword entry systems, but this process can be inefficient and intimidating for many users, particularly if the user is under time pressure or is not experienced in image searching, and can lead to unproductive search results. What makes a particular image similar to another image may be the overall synergistic effect created by the combination of numerous elements of the image. The user, being faced with a checklist of many keywords, may overlook or fail to appreciate how features associated with one or more keywords are contributing to the image's desirability. Out of frustration with the procedure or results of iterative keyword searches, some users may settle for an image that is not really what the user desired or may simply give up, resulting in a dissatisfied user and lost business for the company.
Automated solutions have been attempted that approach the image similarity problem by analyzing the form and structure of the image based on wavelet signatures, color histograms, or other technical analyses. These are of no use if what interests the user is not amenable to this kind of analysis, such as a particular emotion, abstract concept, or business activity depicted in the image.
There is, therefore, a clear need for a method of identifying images of potential interest that lends itself to embodiments allowing use by busy or unsophisticated users.